Statements of Cash Flows (Parenthetical) $ in Millions	12 Months Ended
Dec. 31, 2017 USD ($)
Statement of Cash Flows [Abstract]
Provision from reduction of net deferred tax assets	$ 0.7

Tax Cuts and Jobs Act, Change in Tax Rate, Deferred Tax Asset, Income Tax Expense

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration